The present invention relates to a golf club and a method of manufacturing the same.
In the prior art, Japanese Patent No. 2602253, by the same applicant, describes a golfing iron club head formed by fixing a plurality of members while subjecting them to plastic deformation. This golfing iron club head comprises, as shown for example in FIG. 1 of the above publication, a face member, a weight member provided on a rear surface of the face member, a first cavity portion formed in a rear surface of the face member with a peripheral face in a reverse tapered shape, a second cavity portion formed in a front surface of the weight member opposite to the first cavity portion with a peripheral face in a reverse tapered shape, and a connecting member such as an adhesive or carbon fiber filled and solidified between the first cavity portion and the second cavity portion. In this manner, the face member and the weight member may comprise different materials but are integrally and securely connected to one another.
Also, in the prior art, for such heads, materials having relatively low proof stress and which are easily plastically deformed, such as pure titanium, iron, stainless steel, copper and the like have been used. To obtain higher performance however, the adoption of high-strength materials such as titanium alloy, amorphous alloy and marageing steel has recently been studied. These high-strength materials have a problem in that they are not easily plastically deformed because they have high proof stress and large spring back, and are susceptible to deformation. As a result, in the case of members using high-strength materials, there are problems in that the connection strength is weak, and there is a gap between both members, which is undesirable from an appearance point of view. Specifically, in the case where a face member is fitted to a head body having a window opening as described in Japanese Patent No. 2560272, there is a problem in that the edge of the window opening tends to be bent back at the time of pressing.
One means for solving these problems is adhesion. However, adhesion is not sufficiently strong. Moreover, the method used with the golf club head disclosed in Japanese Patent No. 2560272 by the same applicant is also known. This golf club head as shown in FIG. 1 of the above publication, is one which is provided with a face on a front surface and a shaft connecting portion on one side, and comprises a head body formed with a sole, a cavity portion corresponding to the face formed in the front surface, a through hole formed in the cavity portion and directed rearward and a face member formed from a plate-like metallic material having a lower specific gravity than the head body and fitted into the cavity portion. The cavity portion is formed in a reverse tapered shape, and the face member is pressed into the cavity portion using a press, so that the face member is secured to the cavity portion. Furthermore, Japanese Unexamined Patent Publication No. Hei 9-276453 by the same applicant discloses a manufacturing method for a golf club head comprising a head body having a face, and a weight secured to a rear side of the head body, wherein there is formed a plurality of threaded holes respectively facing the head body and the weight, and the weight is secured while plastically deforming opposite ends of a fixing member in the facing threaded holes.
Utilizing the fixing means disclosed in the above-mentioned Japanese Patent No. 2605253 and Japanese Unexamined Patent Publication No. Hei 9-276453 has been considered. However, it is not possible to secure the face member as described in these publications to a head body having a window opening as in the above-mentioned Japanese Patent No. 2560272.